1. Field
This invention pertains to alternate fuels for internal combustion engines, notably automotive engines. It provides a system for introducing air and low molecular weight hydrocarbon fuel mixtures, notably propane mixtures, in a gaseous (or vaporous) state into the carburetor or intake manifold of an internal combustion engine.
2. State of the Art
It is known that many fuels can be used in the internal combustion engine. For example, vaporized liquid fuels, such as gasoline, ethanol and "gasohols"; producer gas; and normally gaseous (at ambient conditions) hydrocarbons, such as natural gas, hydrogen and propane can be used. Fuels which are normally in vapor state at ambient temperatures are generally pressurized and stored as liquids. A fuel of particular interest is liquid petroleum gas (LPG), a by-product of oil refineries and natural gas plants. LPG is easily liquified under moderate pressure and transforms to the gaseous state readily at normal atmospheric pressures and the temperatures normally present in the proximity of internal combustion engines. LPG is a mixture of low molecular weight hydrocarbon gases predominating in propane and including a significant proportion of butane.
The present disclosure emphasizes the use of propane or LPG fuels because of their practical availability, the experience in the art with the use of such fuels, and their desirable physical properties from the standpoint of handling. Nevertheless, it should be understood that the invention disclosed herein is readily modifiable for use with any of the other fuels which may be used in internal combustion engines.
Several "dual-fuel" systems have been proposed whereby the operator of a motor vehicle may selectively inject gasoline or propane into an internal combustion engine in admixture with the proper amount of air. One example of such a system is that provided by Impco, a division of A. J. Industries, Inc. of Cerritos, Calif., described in the December 1969 issue of Road Test Magazine at pages 62 through 65. In addition, LPG systems have been offered by the International Harvester Company on certain of that company's trucks. The Century LPG system, offered between the years 1965 and 1971, and the Ensign LPG systems, offered between the years 1965 and 1968, are described by "Mitchell Manuals Light Truck Tune-Up" (MM2-118) published by Mitchell Manuals, Inc.
The systems of the prior art, while operable, are generally complex and expensive. They must either be installed by the original manufacturer or by an expert with special knowledge and equipment. Characteristically, a separate carburetor is required to handle the LPG or propane fuel. In other instances, the existing carburetor is modified for the use of LPG fuels and must be again modified to convert back to the use of gasoline. Accordingly, there remains a need in the art for a simple system which can be installed in a motor vehicle by an individual of modest mechanical aptitude using readily available components at moderate cost.